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Original Message

Objective Measurement Results for Cables

Posted by Jon Risch on September 30, 2007 at 21:16:49:

This is bound to be a popular thread, but I wanted to pass along the info, and let folks see what was out there.

At one of the online design sites related to one of the many electronics industry magazines that I get, a portion of a new book (one chapter?) has been posted in 6 parts, and several of the portions have measurement results showing diferences between cables, as well as input/output differences.

The series starts here:
Part 1
http://www.planetanalog.com/showArticle.jhtml?articleID=201802376
http://www.planetanalog.com/features/multimedia/showArticle.jhtml?articleID=201802376
OR AT
http://www.audiodesignline.com/showArticle.jhtml?articleID=201801792

Part 2
http://www.planetanalog.com/showArticle.jhtml?articleID=201803751
OR AT
http://www.audiodesignline.com/showArticle.jhtml?articleID=201803044

Part 3
http://www.planetanalog.com/showArticle.jhtml?articleID=201804426
OR AT
http://www.audiodesignline.com/showArticle.jhtml?articleID=201803044

Part 4
http://www.planetanalog.com/showArticle.jhtml?articleID=201806067
OR AT
http://www.audiodesignline.com/showArticle.jhtml?articleID=201805860

Part 5
http://www.planetanalog.com/showArticle.jhtml?articleID=201807797
OR AT
http://www.audiodesignline.com/howto/showArticle.jhtml?articleID=201807390

Part 6
http://www.planetanalog.com/showArticle.jhtml?articleID=202102592
OR AT
http://www.audiodesignline.com/showArticle.jhtml?articleID=202101992

If you have any trouble with the exact URL's not getting you to the article, try using one of the author's names as a seach term at one site or the other, this should pull up the series in a list.
Authors: Philip Newell and Keith Holland

Book: "Loudspeakers: For Music Recording and Reproduction", Focal Press
The 6 part article appaears to be from Chapter 6 of the book, titled:
Effects of Amplifiers and Cables

They reference research by folks at Cerwin Vega, and BTW, none of the measurement graphs they show in part 5 (where the really interesting measurements are shown) are in the referenced AES papers, as I have copies of both of those, and they do not contain the cable measurement graphs.

I have been keeping an eye out for articles by Alexander Voishvillo, formerly with Cerwin Vega, now with JBL Professional, because he has been repeatedly referencing my AES paper on Multitones, and has done quite a bit of work on Multitones himself. The AES papers cited by Newell and Holland, "Multitone Testing of Sound System Components " Some Results and Conclusions, Part 1: History and Theory" and " .... Part 2: Modeling and Application" by the Cerwin Vega engineering staff (4 engineers are stated as authors, including CV founder, Eugene Czerwinski) are interesting reading, but do not contain the measurement graphs in the Newell and Holland article/book.

Apparently only the book does.

Anyway, I hope that folks will find this article interesting, if anyone gets a cleaner copy of the graphs, I would appreciate a set.

My own impresion of the work presented is that the multitones may not have been fully optimixzed to avoid distortion product cover-up, but rather, chosen for convenience and the generation of a known pattern of potential distortion products (see the referenced AES papers by the CV crew for more details). Thus, the amount and number of distortion products shown may actually be lower than those actually present, due to partial cover-up of some of them.

For instance one very simple choice could have reduced some of the covered-up tones by NOT chosing a simplistic range of ten-to-one for the start and end points of the logrithmically spaced test tones, this alone would avoid the 1 kHz and 10 kHz tones from generating a whole sequence of "covered-up" distortion products, while not stepping on as many of the other tones present. As I outline in my paper, if the upper bound had been chosen to be say, 11.618 kHz instead of 10 kHz even, then almost all of the unneccessary cover-up could have been avoided. Oh, well.

It also looks like it to me that the distortion is a result of an interaction between the amplifier and the cables and loudspeaker load.
Many folks have been for years advocating that amps and cables should be tested with real-world loudspeaker loads, myself included, so as to be as realistic as possible, and to insure that back-EMF issues were included. Newell and Holland have done so.

Finally, I want to point out that this article was primarilly written from the stand point of professional monitoring and use, where certain things are more valued than for home playback, and that this POV does skew the importance various things are given. Those concerned with SOTA home playback would undoubtedly place more emphasis on absolute quality and every last bit of sonic clarity, as opposed to as much on reliability or longevity issues.

Happy reading!


Jon Risch